Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript Build a REST API With Express Modeling Data for the API Getting More from Mongoose

Fernando Balandran
Fernando Balandran
492 Points
Posted by Fernando Balandran
Fernando Balandran
492 Points

Surely there has to be a better way to handle callbacks?

When you cleaned the three saves with the create method, and cleaned that a bit. You said ok looks much better and honestly it still looked like a complete mess to my python and java eyes. It is quite hard to track opening and closing braces in all those nested callbacks.

With that being said, I haven't done much programming in javascript, please tell me there is a better way to handle callbacks course was going pretty good for me until I saw the callback hell.

2 Answers

Brett Carter
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Brett Carter
Full Stack JavaScript Techdegree Graduate 17,766 Points
Brett Carter
.a{fill-rule:evenodd;}techdegree seal-36
Brett Carter
Full Stack JavaScript Techdegree Graduate 17,766 Points

I wrote this with promises for anyone who is interested. Note that the findSameColor static method does not take a callback parameter which using promises.

findSameColor without callback:

  AnimalSchema.methods.findSameColor = function() {
    return this.model('Animal').find({color: this.color});
  }

Promise chain (not perfect, but much better):

  Animal.remove({})
    .then(_ => {return Animal.create(animalData)})
    .then(_ => {return Animal.findOne({type: 'elephant'});})
    .then(elephant => {return elephant.findSameColor();})
    .then((coloredAnimals) =>{
      return coloredAnimals.forEach(animal => {
        console.log(`${animal.name} the ${animal.color} is a ${animal.size} ${animal.type}`);
      });
    })
    .then(_ => db.close(_ => console.log('db connection closed')))
    .catch(err => console.log(err));
});

Would be cleaner with async/await, which Mongo 5 now supports natively.

Fernando Balandran
Fernando Balandran
492 Points
Fernando Balandran
Fernando Balandran
492 Points

That looks much cleaner and more readable. Thanks Brett!

Fernando Balandran
Fernando Balandran
492 Points
Fernando Balandran
Fernando Balandran
492 Points

Thanks! That's exactly what I was looking for. Promises are much better.